1. Field of the Invention
The present invention relates in general to the field of hand tools and more particularly to a tape measure with a braking device used to control the retraction of the blade in a retractable blade tape measure.
2. Background
A tape measure of the type that will incorporate the present invention includes an outer case with a metal tape blade retractably mounted within the case. A retracting mechanism retracts the tape blade into the case. A hook at the end of the tape provides a stop for preventing the end of the tape from retracting inside the case. A clip allows the tape measure to be attached to a belt. A lock releasably secures the tape blade in the desired extended position. The lock typically includes a toggle switch with a lock shoe associated with the toggle switch. When one end of the toggle is depressed, the lock shoe is moved downward against the inside bottom of the case. Pushing the other end of the toggle releases the lock shoe, allowing the tape blade to freely retract into the case.
When the tape blade is being retracted into the case, the retracting mechanism and the portion of the tape blade already retracted into the case build up inertia. This inertia causes the hook at the end of the tape blade to strike the case with substantial force when the blade is fully retracted. The hook and the adjacent portion of the tape blade can be damaged by this force. This problem was recognized by John J. Evans, Jr. and is described in Canadian Pat. No. 1,193,853 issued Sept. 24, 1985 as follows "Blade end failures may also result from excessive whipping of the blade end attachment against the tape housing as the blade is retracted into the housing, particularly if blade retraction is assisted by a spring return".